JPH1120105A - Release film having slight contaminating property - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a release film wherein impurities in a release layer are few and a shift of the impurities in a polyester film into an adhesive tape is suppressed and which is useful for a protective film of an adhesive used in a wafer grinding process or a dicing process on the occasion of manufacture of a semiconductor, or others. SOLUTION: This release film is constituted in such a manner that the resin obtained by a method wherein modified silicone resin containing dimethyl polysiloxane having a phenyl group, as a constituent, is made to react in the rate of 0-30 mol.% on organic resin constituted of at least one kind of resin selected from alkyd resin and acrylic resin and of melamine resin is provided as a release layer at least on one surface of a polyester film. In this case, a wafer contamination value of an adhesive tape for a semiconductor manufacturing process, wherein the release film is used as a protective film, is made 200 pcs. or less.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a release film using a polyester film as a base film, and more particularly to a release film having excellent peeling behavior when used as a protective film for an adhesive tape for a semiconductor manufacturing process. Release film useful for a protective film of an adhesive used in a wafer polishing process or a dicing process in the production of semiconductors, in which impurities in a mold layer are small and impurities in a polyester film are prevented from migrating to an adhesive tape. About.

[0002]

2. Description of the Related Art In a process of polishing a back surface of a wafer (a back grinding process) and a process of cutting an IC chip from a completed wafer (a dicing process) at the time of manufacturing a semiconductor, an adhesive tape on which various adhesives are laminated is used. Used for fixing. In the back grinding process, the wafer with the circuit formed on the front surface is polished on the back surface while being fixed to the adhesive tape, and the adhesive force of the adhesive is reduced by UV irradiation, heating, or the like, and then moves to the next dicing process. In the dicing process, the wafers fixed on the adhesive tape are cut into individual IC chips, and the adhesive force of the adhesive is reduced by UV irradiation or heating as in the back grinding process, and then the wafers are taken out one by one. The extracted IC chip is transferred to the next bonding step and molding step.

Usually, the pressure-sensitive adhesive tape is stored in a form in which the surface of the pressure-sensitive adhesive layer is protected by a release film, and is used after being peeled off and removed from the release film in the above-mentioned back grinding step and dicing step. You. In the back grinding process, since the pressure-sensitive adhesive directly contacts the circuit surface, even if there is even a small amount of impurities such as reaction residues after the pressure-sensitive adhesive tape is peeled off, circuit conduction failure may occur. In recent years, since the size of semiconductor chips has become extremely small and thin, even if there is even a small amount of impurities on the wafer surface, cracks and the like will occur due to poor adhesion starting from that part in the molding process, reducing the product yield. There is a problem.

The protective film of the pressure-sensitive adhesive tape is, for example, provided on a polyester film surface with a primer layer obtained by crosslinking a silane coupling agent, and a silicone release layer provided thereon (Japanese Patent Laid-Open No. 1-5838). No. 1) has been conventionally used. However, in these release films, impurities (for example, oligomers and metal compounds used as polymerization catalysts) in the polyester film easily migrate through the primer layer and the silicone release layer and accumulate on the surface of the release layer. Impurities accumulated on the surface
Transferred to the surface of the pressure-sensitive adhesive layer of the pressure-sensitive adhesive tape, and retransferred to the wafer in the back grinding process and dicing process in the above semiconductor production, causing various problems on the circuit on the wafer surface and cracking in the molding process As a result, the yield of IC chips is reduced.

In addition, when impurities (such as uncured silicone monomers and oligomers) in the silicone resin are present in a certain amount or more, or when the solvent resistance of the silicone resin release layer is low, the adhesive during the adhesive application in the production of an adhesive tape is poor. There is a problem that a component of the release layer is dissolved by the solvent of the agent and is deposited on the surface of the pressure-sensitive adhesive after the solvent is dried.

[0006]

SUMMARY OF THE INVENTION An object of the present invention is to eliminate the drawbacks of the prior art, to reduce the amount of impurities in the release layer and to prevent the impurities in the polyester film from migrating to the surface of the pressure-sensitive adhesive tape. An object of the present invention is to provide a release film useful as a protective film on the surface of the pressure-sensitive adhesive of a pressure-sensitive adhesive tape used in a back grinding step or a dicing step in semiconductor production.

[0007]

According to the present invention, there is provided a dimethylpolysiloxane having a phenyl group on at least one surface of a polyester film with respect to at least one resin selected from an alkyd resin and an acrylic resin and an organic resin comprising a melamine resin. A release film provided as a release layer with a resin obtained by reacting a modified silicone resin containing siloxane as a component at a rate of 0 to 30 mol%, for a semiconductor manufacturing process using the release film as a protective film. A release film having a wafer contamination value of the adhesive tape of 200 or less. Hereinafter, the present invention will be described in detail.

[Polyester Film] In the present invention, a polyester film is used as a film base material. For applications requiring transparency, a polyester film having good transparency is preferably used. Axial stretched polyester films are particularly preferred. For applications requiring light-shielding properties, it is preferable to use a polyester film containing an inorganic pigment.
A biaxially stretched polyester film containing a pigment such as O ₂ or SiO ₂ is particularly preferred.

The polyester constituting such a polyester film is a linear saturated polyester synthesized from an aromatic dibasic acid or an ester-forming derivative thereof and a diol or an ester-forming derivative thereof.

As such polyesters, polyethylene terephthalate, polyethylene isophthalate, polytetramethylene terephthalate, poly (1,4-cyclohexylene methylene terephthalate), polyethylene
Preferred examples include 2,6-naphthalenedicarboxylate, and particularly polyethylene terephthalate. These polyesters are preferably homopolymers, but a small amount of copolymer components (for example, 5 mol%
The following) may be a copolymerized polyester. Also,
These resins may be blended with other resins in a small proportion (for example, 10% by weight or less).

In the case where the polyester constituting the present invention is, for example, polyethylene terephthalate, terephthalic acid and ethylene glycol are mixed, and the mixture is heated with stirring to perform an esterification reaction. It can be obtained by adding a reaction catalyst and heating while stirring under reduced pressure to cause a polycondensation reaction. Alternatively, for example, dimethyl phthalate and ethylene glycol are mixed, and a transesterification catalyst is added,
It can be obtained by performing a transesterification reaction by heating while stirring, adding a polycondensation catalyst to the obtained transesterification product, and heating and performing a polycondensation reaction while stirring under reduced pressure.

As the polycondensation reaction catalyst, any known compound can be used, but a germanium compound is preferable in that the amounts of metal elements and oligomers in the polyester film can be reduced, and examples thereof include germanium oxide. .

As such germanium oxide, (a) amorphous germanium oxide (b) fine crystalline germanium oxide (c) a solution of germanium oxide dissolved in water can be used.

The amount of the germanium compound used for the polycondensation reaction catalyst is preferably from 10 to 200 ppm, more preferably from 20 to 150 ppm, as a metal element of germanium remaining in the polyester. When the amount of the germanium compound is within this range, it is preferable because oligomers precipitated on the surface of the release layer of the release film can be suppressed.

In the case of a polyester obtained by performing a transesterification reaction, it is preferable to use a titanium compound as a transesterification catalyst because oligomers that precipitate on the surface of the release layer of the release film can be suppressed. Examples of the titanium compound include titanium acetate, titanium benzoate, titanium tetrabutoxide, titanium tetraisopropoxide, and titanium trimellitate.

The above-mentioned polyester may contain other improving agents. For example, a compound having a sulfonate group such as sodium dodecylbenzene sulfonate can be contained as an antistatic agent. Polyesters without these modifiers can also be used.

The above-mentioned polyester has an average particle diameter of 0.0 as a lubricant in order to improve the slipperiness of the film.
Organic or inorganic fine particles having a size of about 1 to
It can be contained at a blending ratio of 005 to 20% by weight. Specific examples of such fine particles include organic fine particles such as inorganic fine particles such as silicon oxide, crosslinked polystyrene resin fine particles, crosslinked silicone resin fine particles, and crosslinked acrylic resin fine particles. Among these, organic fine particles such as resin fine particles are particularly preferable.

The polyester film in the present invention comprises:
It can be manufactured by a conventionally known method. For example, a biaxially stretched polyester film is obtained by drying a polyester, melting it with an extruder, and forming a die (for example, a T-die,
(I-die or the like), extruded onto a rotary cooling drum, quenched to obtain an unstretched film, and then stretched in the biaxial direction, and heat-fixed if necessary. The thickness of the film is not particularly limited, but is preferably 5 to 250 μm.

[Primer layer] In the present invention, a compound represented by the following formula (I) is crosslinked on at least one surface of the polyester film in order to suppress migration of impurities in the polyester to the surface of the release layer. 0.02-2
A primer layer having a thickness of μm may be provided.

[0020]

Embedded image in _{Y-Si-X 3 ...... (} I) [ Formula (I), X is an alkoxy group, Y epoxy group, an amino group, a vinyl group, reactive with a methacryl group, a mercapto group or an alkoxy group Represents an organic functional group. ]

In the compound represented by the above formula (I),
X is an alkoxy group, but is preferably a methoxy group or an ethoxy group, and particularly preferably a methoxy group because the rate of cross-linking and polymerizing the primer layer is high.

In the compound represented by the formula (I), Y is preferably a reactive organic functional group having an epoxy group or an amino group, and particularly Y is a reactive organic functional group having an epoxy group. This is preferable because the adhesion between the primer layer and the polyester film becomes good and the effect of suppressing the migration of impurities in the polyester to the surface of the release layer is good. Examples of such a reactive organic functional group include a 3-glycidoxypropyl group and a 2-glycidoxypropyl group.
And a (3,4-epoxycyclohexyl) ethyl group.

The compound represented by the above formula (I) includes
For example, compounds represented by the following formulas (II) and (III) are particularly preferred.

[0024]

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[0025]

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Such a primer layer is formed, for example, by dissolving or dispersing the compound represented by the above formula (I) in water,
The coating can be performed by coating on at least one surface of the polyester film, heating at a temperature of, for example, 120 to 210 ° C. for 10 to 60 seconds to dry and remove water, and crosslinking and curing.

The primer layer has a thickness of 0.02 to 0.02.
2 μm. If the thickness is less than 0.02 μm,
The effect of suppressing migration of impurities in the polyester from the surface of the release layer to the adhesive tape is insufficient, and if it exceeds 2 μm, the blocking resistance of the polyester film on which the primer layer is laminated becomes poor.

[Release Layer] In the present invention, on at least one surface of the polyester film, at least one resin selected from an alkyd resin and an acrylic resin and an organic resin composed of a melamine resin are used. A resin obtained by reacting a modified silicone resin containing siloxane as a component at a rate of 0 to 30 mol% is provided as a release layer.

The organic resin comprises at least one resin selected from an alkyd resin and an acrylic resin and a melamine resin. The compounding ratio of the organic resin is 100 mol based on the total amount of the alkyd resin and the acrylic resin. It is preferably from 5 to 200 mol.

In the resin composition of the present invention, the alkyd resin and / or the acrylic resin may be mixed with a silicone resin before coating or may be formed in advance with a copolymer with the silicone resin. Good. The melamine resin mainly acts to crosslink with the alkyd resin to cure the release layer.

The above-mentioned alkyd resin has a skeleton of a condensate of a polybasic acid such as phthalic anhydride as an acid component and a polyhydric alcohol such as glycerin or ethylene glycol as a glycol component. It is a resin modified with. For example, castor oil-modified alkyd resin, soybean oil-modified alkyd resin, linseed oil-modified alkyd resin, and the like are used, and alkyd resins modified with various fatty acids can be used in any combination. In the resin composition of the present invention, for example, a silicone resin can be blended during or after the production of the alkyd resin, and the alkyd resin can be graft-copolymerized with the silicone resin.

The acrylic resin is blended in order to make the release layer tough and to improve the wettability of the surface of the release layer. As the acrylic resin, for example, polyacrylic acid, polymethacrylic acid, polymethyl methacrylate, or the like can be used. The mixing ratio of the alkyd resin and the acrylic resin can be set according to the purpose because various physical properties can be obtained by the mixing ratio, and the acrylic resin or the alkyd resin can be used alone.

As the melamine resin, for example, methylated melamine resin, butylated melamine resin, methylated urea melamine resin and the like can be used. It is preferable to use the melamine resin in a ratio of 5 to 200 mol based on 100 mol of the total amount of the alkyd resin and the acrylic resin.
An acidic catalyst such as sodium paratoluenesulfonate can be used as a curing catalyst for this crosslinking reaction.

The modified silicone resin used in the present invention is:
The modified silicone resin contains, as a component, dimethylpolysiloxane having a phenyl group represented by the following formula (IV).

[0035]

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[In the formula (IV), R is a methyl group or a phenyl group, m and n are each 1 or more, and m + n = 50.
~ 2000. In the above formula (IV),

[0037]

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It should be understood that does not mean block connection, but merely indicates that the sum of the respective units is m, n. Therefore,
Each unit in the above formula (IV) may be randomly bonded or may be block-bonded.

In the present invention, the modified silicone resin containing, as a component, polydimethylsiloxane having a phenyl group represented by the above formula (IV) is at least one resin selected from alkyd resins and acrylic resins, and melamine resins. 0 to 30 mol% based on the organic resin
Preferably 5 to 30 mol%, more preferably 10 to
A release layer is formed using a resin obtained by reacting at a ratio of 20 mol%. When the ratio exceeds 30 mol%, an unreacted resin component increases, and an adhesive tape using a release film as a protective film. Is unfavorable because the contamination value of the wafer becomes large.

[Method of Coating Release Layer] In the present invention,
A release layer is provided on at least one surface of the polyester film, and the release layer is coated with a coating liquid containing a modified silicone resin containing, for example, an alkyd resin, a melamine resin, and a dimethylpolysiloxane having a phenyl group as components. And a drying and curing reaction. The heating conditions are, for example, 80 to
It is preferable to set the temperature at 160 ° C. for 10 to 120 seconds, particularly at 100 to 150 ° C. for 15 to 60 seconds, since the drying and curing reaction becomes sufficient. In addition, as a coating method of the coating liquid, any known coating method can be applied, and examples thereof include a roll coater method and a blade coater method. However, the coating method is not limited to these methods. Further, the coating liquid may be an organic solvent type or an aqueous dispersion emulsion type.

[0041]

The present invention will be further described below with reference to examples. In addition, each characteristic value of the film was measured by the following method.

(1) Measurement of Wafer Contamination Value A UV-curable pressure-sensitive adhesive having the following composition was applied to the release film of the sample with a geser so that the thickness of the pressure-sensitive adhesive layer after drying was 20 μm, and the solvent was removed. After evaporating with a dryer, an adhesive tape was prepared by laminating with a biaxially stretched polypropylene film. The pressure-sensitive adhesive layer of the pressure-sensitive adhesive tape is cured by UV irradiation, and the adhesive strength is reduced.

Next, an adhesive tape was prepared in the same manner as described above, using a polyester film instead of the release film as a blank.

On a 4-inch clean silicon wafer,
After applying an adhesive tape and performing UV irradiation, the tape was peeled off. Laser surface inspection equipment (LS-5, manufactured by Hitachi Electronics Engineering)
000), the residue of 0.25 μm or more was counted, and the value obtained by subtracting the blank value (contamination value caused only by the adhesive) was taken as the wafer contamination value.

<Adhesive composition> 2-ethylhexyl acrylate / acrylic acid copolymer (95/5) 60 parts Hydroxy-terminated polybutadiene / acrylonitrile copolymer (83/17) 15 parts Dioctyl maleate 5 parts 2-ethylhexyl acrylate 10 Part Tetraethylene glycol diacrylate 10 parts Benzoin ethyl ether 3 parts Ethyl acetate (solvent) 200 parts

(2) Analysis of Metal Elements in Polyester A predetermined amount of a polyester film is decomposed with a mixed acid of sulfuric acid and nitric acid, diluted with pure water to a predetermined volume, and then subjected to inductively coupled high frequency plasma (ICP) emission spectroscopy. The metal was quantitatively analyzed to determine the metal element concentration in the polyester.

(3) Residual Adhesion Rate A polyester adhesive tape (Nitto 31B) was used according to JIS.
・ Cold rolled stainless steel sheet (SUS
The peeling force after application to step 304) is measured, and the measured value is defined as a basic adhesive force (f ₀ ). In addition, the polyester adhesive tape was pressed against the release layer coating surface of the sample film with a 5 kg pressure roller, left for 30 seconds, and then the adhesive tape was peeled off.
Then, the peeled adhesive tape is stuck on the above stainless steel plate, the peeling force of the bonded portion is measured, and the measured value is defined as a residual adhesive force (f). From the obtained basic adhesive strength (f ₀ ) and residual adhesive strength (f), a residual adhesive rate was determined using the following equation.

[0048]

## EQU1 ## Residual adhesion rate (%) = (f / f ₀ ) × 100

(4) Peeling strength (rubbing test) A polyester pressure-sensitive adhesive tape (Nitto 31B) was adhered to the surface of the release layer of the polyester film, pressed with a pressure roller of 5 kg, left standing for 20 hours, and then separated from the release layer with the pressure-sensitive adhesive tape. The peeling force (g / in) was measured with a tensile tester.

Example 1 Dimethyl terephthalate and ethylene glycol were used as starting materials, tetrabutyl titanate was used as a transesterification catalyst in an amount of 0.015 part by weight per 100 parts by weight of dimethyl terephthalate, and germanium oxide was used as a polycondensation reaction catalyst. Polyethylene terephthalate obtained by using 0.01 part by weight with respect to 100 parts by weight of dimethyl terephthalate (having an intrinsic viscosity of 0.65 measured in orthochlorophenol at 35 ° C. and SiO ₂ particles having an average particle diameter of 0.17 μm of 0.1 part by weight). (95% by weight) was melt-extruded on a rotary cooling drum maintained at 20 ° C. to obtain an unstretched film having a thickness of 950 μm, and then stretched 3.5 times in the machine axis direction (longitudinal direction). After forming a uniaxially stretched film, 3
5% by weight of glycidoxypropyltrimethoxysilane
The aqueous solution was applied by a kiss coat method, and dried under the conditions of 105 ° C. × 10 seconds. The average coating amount at this time was 100 mg / m ² in terms of solid content. Subsequently, the film is stretched 3.9 times in the transverse direction at 105 ° C., and heat-treated at 220 ° C.
A biaxially stretched polyester film having a primer layer having a thickness of 0.025 μm coated on one side of the base film was obtained. The concentration of the metal element in the polyester was 8 ppm for the Ti metal element and 30 ppm for the Ge metal element.

Next, castor oil-modified alkyd resin 75
mol%, butylated melamine resin 10 mol% and in the above formula (IV), R is a phenyl group and n + m is 20
0, m / (n + m): 15% by mole of phenyl-substituted dimethylpolysiloxane having a modified ratio of 0.25, toluene / methyl ethyl ketone (50% by weight / 50% by weight)
A coating solution dissolved in a mixed solvent so that the solid content concentration was 3% by weight was prepared.

Next, this coating liquid was applied to the previously obtained biaxially stretched polyester film at a coating amount of 6 g / m ² (wet), and a drying and curing reaction was performed at a heating temperature of 150 ° C. and a heating time of 1 minute. Then, a release film having a release layer thickness of 0.2 μm was prepared. Table 1 shows the characteristics of the release film.

Example 2 A release film was prepared in the same manner as in Example 1, except that castor oil-modified alkyd resin was 62 mol%, butylated melamine resin was 8 mol%, and phenyl-substituted dimethylpolysiloxane was 30 mol%. Table 1 shows the characteristics of the release film.

Example 3 A release film was prepared in the same manner as in Example 1, except that the castor oil-modified alkyd resin was 88 mol%, the butylated melamine resin was 12 mol%, and the phenyl-substituted dimethylpolysiloxane was 0 mol%. Table 1 shows the characteristics of the release film.

Comparative Example 1 A release film was prepared in the same manner as in Example 1, except that castor oil-modified alkyd resin was 45 mol%, butylated melamine resin was 5 mol%, and phenyl-substituted dimethylpolysiloxane was 50 mol%. Table 1 shows the characteristics of the release film.

Comparative Example 2 A release film was prepared in the same manner as in Example 1 except that the butylated melamine resin was not added. Table 1 shows the characteristics of the release film.

Example 4 Separation was carried out in the same manner as in Example 1 except that 70 mol% of an acrylic resin containing polymethyl methacrylate as a main component, 15 mol% of a butylated melamine resin and 15 mol% of a phenyl-substituted dimethylpolysiloxane were used. A mold film was made. Table 1 shows the characteristics of the release film.

Example 5 35 mol% of an acrylic resin containing polymethyl methacrylate as a main component, 35 mol% of a castor oil-modified alkyd resin, and a butylated melamine resin 15
A release film was prepared in the same manner as in Example 1, except that the mol% and the phenyl-substituted dimethylpolysiloxane were changed to 15 mol%. Table 1 shows the characteristics of the release film.

Example 6 Polyethylene terephthalate was used starting from dimethyl terephthalate and ethylene glycol, and manganese dioxide was used as a transesterification catalyst in an amount of 0.1 to 100 parts by weight of dimethyl terephthalate.
Antimony trioxide as a polycondensation reaction catalyst was used in an amount of 0.2 parts by weight based on 100 parts by weight of dimethyl terephthalate.
With the exception of changing the polyethylene terephthalate obtained by using 0.66 parts by weight (intrinsic viscosity measured in orthochlorophenol at 35 ° C. of 0.65 and containing 0.05% by weight of SiO ₂ particles having an average particle size of 0.17 μm). A release film was prepared in the same manner as in Example 1. Table 1 shows the characteristics of the release film. The concentration of the metal element in the polyester was 100 ppm for the Mn metal element and 40 ppm for the Sb metal element.
It was 0 ppm.

[0060]

[Table 1]

[0061]

According to the present invention, the amount of impurities in the release layer is small, and the migration of impurities in the polyester film to the release layer is suppressed. It is possible to provide a release film useful as a protective film for a pressure-sensitive adhesive.

Claims (5)

[Claims] 1. A modified silicone resin comprising, on at least one surface of a polyester film, at least one resin selected from an alkyd resin and an acrylic resin and an organic resin composed of a melamine resin, and a dimethylpolysiloxane having a phenyl group as a component. 0 to 30 mol%
The release film provided with a resin obtained by reacting at a ratio of the release film as a release layer, wherein the wafer contamination value of the adhesive tape for a semiconductor manufacturing process using the release film as a protective film is 200 or less. Mold film. 2. The melamine resin is used in an amount of 5 to 200 m with respect to a total amount of 100 mol of the alkyd resin and the acrylic resin.
The release film according to claim 1, which is ol. 3. A compound of the following formula (I) crosslinked between the polyester film surface and the release layer.
The release film according to claim 1, wherein a primer layer having a thickness of from 02 to 2 µm is provided. ## STR1 _{Y-Si-X 3 ...... (} I) [ Formula (I), X is an alkoxy group, Y epoxy group, an amino group, a vinyl group, reactive with a methacryl group, a mercapto group or an alkoxy group Represents an organic functional group. ] 4. The release film according to claim 1, wherein the polyester film is a polyethylene terephthalate film or a polyethylene-2,6-naphthalate film. 5. The release film according to claim 1, which is used as a protective film for an adhesive tape used in a wafer polishing step or a dicing step in semiconductor production.